LaTeX

LaTeX is a typesetting system for publishing mathematics. Originally developed in the 1970s by Donald Knuth, it is now used by virtually all mathematics journals. Thus learning to use LaTeX is a universal rite of passage for mathematicians. LaTeX itself is available free of charge, and the software itself is under an open-source license.

My advice is to just install LaTeX and start working. Use one of the template files below to get started.

LaTeX distributions and editors

TeX Live is an extremely comprehensive, free LaTeX distribution. It includes a bare-bones LaTeX editor. I can lend you a DVD to install it, or you can install it over the internet or download the DVD yourself.